Universidad de Magallanes
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Synthesis, characterisation, crystal structure and antimicrobial evaluation of novel 6-alkoxyergosta-4,6,8(14),22-tetraen-3-one derived from natural ergosta-5,7,22-trien-3β-ol
No full textIn this study, we report a facile transformation starting from 5 alpha-hydroxyergosta-7,22-dien-3,6-dione (1) to afford two novel compounds: 6-methoxyergosta-4,6,8(14),22-tetraen-3-one (2) and 6-ethoxyergosta-4,6,8(14),22-tetraen-3-one (3) using alcoholic acid catalysis. Their structures were elucidated using NMR experiments, FT-IR, MS and X-ray analysis. These compounds were evaluated for antibacterial activity using the disk and broth diffusion test. In those tests, compound 3 was found to be the most significant antibacterial agent. In general, compounds 1-3 showed inhibition zone in the range of 7.00-12.3 mm for S. aureus and S. mutans, meanwhile for Gram-negative bacteria E. coli and Pseudomonas sp. was found to be in the range of 7.00-8.00 mm. For the most active, compound 3, MIC was significantly lower than that reported for ergosterol, in a value of 160 mu g/mL. Overall, these compounds were more active than their natural precursor
Southern limit of the Patagonian Ice Sheet
No full textThe southern limit of the Patagonian Ice Sheet at glacial maxima is poorly constrained due to a paucity of field data. This particularly applies to southern outlet glaciers of the Cordillera Darwin whose full extents have been debated by glacial geologists since 1899 CE, introducing uncertainty into estimates of total ice volume. Here we report on the stratigraphy of exposed stratigraphic sections on the west coast of Isla Hermite which include glacial diamict with discontinuous boulder pavement, overlain by successions of peats and sandy silt. The location of these sections, orientation of clasts within the glacial diamict, and geomorphology of the adjacent marine trough, suggest that an ice stream extended south from an ice centre at Cordillera Darwin across an extended Magellan outwash plain, through Paso Mantellero, to Islas Hermite and Cabo de Hornos (Cape Horn). This was similar in extent to the Canal Beagle and Lago Fagnano Ice Lobes which extended to the east. Retreat occurred sometime before 12,880 cal yr BP based on radiocarbon dated peat macrofossils immediately overlying the glacial diamict. We discuss whether this is a close minimum age, or a product of delayed onset of peat accumulation at the sampling site
A global-level assessment of gulls (Larus spp.) as bioindicators of trace elements in coastal ecosystems
No full textABSTRACT. Anthropogenic activities and the demand for trace elements have risen, causing an increase in their environmental levels, which could affect biota. High levels of trace elements in living beings have been associated with toxicity, metabolic disorders, oxidative stress, and cancer. Seabirds, such as gulls, have been used as bioindicators of environmental pollution caused by anthropogenic sources. Gulls are widely distributed worldwide, usually occupying high trophic levels, and living close to humans. Among gulls, Larus spp. are omnivorous, predominantly carnivorous, nest on the ground, and capture live food or steal it opportunistically. The present work summarizes the data of trace elements found in eggs, feathers, blood, and feces, among other internal tissues, of several gull species of the genus Larus around the world. Most of the reports are from the Northern Hemisphere (70%), particularly from Europe and North America. The elements Cd, Hg, Mn, Pb, and Se are the most studied (54%), among which Hg represents about 19%. On the other hand, there is no information for lesser-known trace elements such as Rb, Ti, new technology elements (e.g. Ge, Re, Ta), rare earth elements (e.g. Ce, La, Y), or elements of the platinum group (e.g. Os, Ir, Ru). Even though Larus spp. is a suitable bioindicator of chemical contamination in marine ecosystems, only 28 of the 53 species of the Larus genus have been used on trace elements pollution. Future research should address lesser-known elements which are increasingly used by new technologies
Variations on primary metabolites of the carrageenan-producing red algae Sarcopeltis skottsbergii from Chile and Sarcopeltis antarctica from Antarctic Peninsula
No full textSeveral studies reported that gametophytes and tetrasporophytes of Gigartinaceae produce different carrageenan types, as observed in Sarcopeltis species although they have isomorphic haploid and diploid phases. Cystocarpic and non-fertile plants of Sarcopeltis (ex Gigartina) skottsbergii produced kappa-carrageenans, while tetrasporophytes produced lambda-carrageenans, and yields were higher in cystocarpic and sterile specimens than in tetrasporophytes. However, comparison on the other primary metabolites among different life history phases still needed to be investigated. Then, we tested the hypothesis if the variation on primary metabolites (pigments, proteins and carbohydrates) are related to the life history phases of Sarcopeltis antarctica and Sarcopeltis skottsbergii, and/or are influenced by abiotic factors. Primary metabolites of S. antarctica varied according to the life-history phases: non-fertile specimens presented higher phycobiliprotein concentrations, tetrasporophytes presented higher chlorophyll a concentrations, and cystocarpic specimens presented higher concentrations of proteins, polysaccharides and floridean starch. However, primary metabolites of S. skottsbergii varied in response to some abiotic factors (nutrients, temperature and salinity), since principal component analysis evidenced two groups; one was related by the higher nitrate and phosphate concentrations, and the other was related to the higher temperatures and lower salinities. Concentrations of floridean starch, low molecular weight carbohydrates, and polysaccharides are higher in S. antarctica than in S. skottsbergii, which could be related to the protective role of these compounds against salinity variation and low temperatures faced in the Antarctic extreme environments
Past climate-driven range shifts structuring intraspecific biodiversity levels of the giant kelp (Macrocystis pyrifera) at global scales
No full textThe paradigm of past climate-driven range shifts structuring the distribution of marine intraspecific biodiversity lacks replication in biological models exposed to comparable limiting conditions in independent regions. This may lead to confounding effects unlinked to climate drivers. We aim to fill in this gap by asking whether the global distribution of intraspecific biodiversity of giant kelp (Macrocystis pyrifera) is explained by past climate changes occurring across the two hemispheres. We compared the species' population genetic diversity and structure inferred with microsatellite markers, with range shifts and long-term refugial regions predicted with species distribution modelling (SDM) from the last glacial maximum (LGM) to the present. The broad antitropical distribution of Macrocystis pyrifera is composed by six significantly differentiated genetic groups, for which current genetic diversity levels match the expectations of past climate changes. Range shifts from the LGM to the present structured low latitude refugial regions where genetic relics with higher and unique diversity were found (particularly in the Channel Islands of California and in Peru), while post-glacial expansions following similar to 40% range contraction explained extensive regions with homogenous reduced diversity. The estimated effect of past climate-driven range shifts was comparable between hemispheres, largely demonstrating that the distribution of intraspecific marine biodiversity can be structured by comparable evolutionary forces across the global ocean. Additionally, the differentiation and endemicity of regional genetic groups, confers high conservation value to these localized intraspecific biodiversity hotspots of giant kelp forests
Relict duck-billed dinosaurs survived into the last age of the dinosaurs in subantarctic Chile
No full textIn the dusk of the Mesozoic, advanced duck-billed dinosaurs (Hadrosauridae) were so successful that they likely outcompeted other herbivores, contributing to declines in dinosaur diversity. From Laurasia, hadrosaurids dis-persed widely, colonizing Africa, South America, and, allegedly, Antarctica. Here, we present the first species of a duck-billed dinosaur from a subantarctic region, Gonkoken nanoi, of early Maastrichtian age in Magallanes, Chile. Unlike duckbills further north in Patagonia, Gonkoken descends from North American forms diverging shortly before the origin of Hadrosauridae. However, at the time, non-hadrosaurids in North America had become replaced by hadrosaurids. We propose that the ancestors of Gonkoken arrived earlier in South America and reached further south, into regions where hadrosaurids never arrived: All alleged subantarctic and Antarctic remains of hadrosaurids could belong to non-hadrosaurid duckbills like Gonkoken. Dinosaur faunas of the world underwent qualitatively different changes before the Cretaceous-Paleogene asteroid impact, which should be considered when discussing their possible vulnerability
Impacts of leaks and gas accumulation on closed chamber methods for measuring methane and carbon dioxide fluxes from tree stems
No full textAccurate measurements of methane (CH4) and carbon dioxide (CO2) fluxes from tree stems are important for understanding greenhouse gas emissions. Closed chamber methods are commonly employed for this purpose; however, leaks between the chamber and the atmosphere as well as gas accumulation, known as the concentration buildup effect, can impact flux measurements significantly. In this study, we investigated the impacts of concentration buildup and leaks on semi-rigid closed chamber methods. Field measurements were conducted on six tree species, including three species from a Mexican mangrove ecosystem and three species from a Magellanic sub-Antarctic forest. Systematic observations revealed significant leak flow rates, ranging from 0.00 to 465 L h 1, with a median value of 1.25± 75.67 L h-1. We tested the efficacy of using cement to reduce leaks, achieving a leak flow rate reduction of 46-98 % without complete elimination. Our study also demonstrates a clear and substantial impact of concentration buildup on CH4 flux measurements, while CO2 flux measurements were relatively less affected across all tree species studied. Our results show that the combined effects of leaks and concentration buildup can lead to an underestimation of CH4 emissions by an average of 40± 20 % and CO2 emissions by 22± 22 %, depending on the bark roughness. Based on these findings, we recall a straightforward yet effective method to minimize experimental errors associated with these phenomena, previously established, and reiterated in the current context, for calculating emissions that considers effects of leaks and concentration buildup, while eliminating the need for separate determinations of these phenomena. Overall, the results, combined with a literature review, suggest that our current estimates of GHG flux from tree stems are currently underestimated
The Internal development model and the National Oil Company occupation role of the coastal space of the Strait of Magellan
No full textChile estableció entre 1939 y 1973 un modelo de desarrollo hacia dentro, base de la puesta en marcha y sofisticación de un Estado desarrollista. Como agente transformador de la economía, las decisiones estatales impactaron a los territorios debido a la emergencia de una política de Industrialización por Sustitución de Importaciones (ISI), logrando vehicular la introducción de saberes y tecnologías mediando una nueva institucionalidad promotora, la Corporación de Fomento de la Producción (CORFO, 1939) y una nueva empresa estatal, la Empresa Nacional del Petróleo (ENAP, 1950). Analizando las implantaciones de la industria de los hidrocarburos en Magallanes, nos interesó demostrar que la ENAP contribuyó a estructurar a través de sus infraestructuras, terminales y campamentos la ocupación del espacio litoral y reforzó el rol del estrecho de Magallanes como un área de comunicación primero y explotación después; lo que no habría sido posible sin establecerse condiciones políticas, sociales y económicas previas
The exploration of marginal spaces in Central-West Patagonia and the role of discontinuous occupation of forests and highlands
No full textRegions with low population density, which are geographically marginal with respect to the most frequently occupied areas, are theoretically more prone to discontinuities in human occupation. This is the case in Central-West Patagonia (Chile, South America), where the discontinuities have had different characteristics and extents, some even lasting millennia. This work proposes that, given the prolonged and repeated periods of abandonment of some areas in Central-West Patagonia, its exploration is not to be considered a unique, one-time process; rather, it occurred more than once throughout its history. Because ascertaining each exploration is complex, this process can be investigated by focusing on spaces that represent the incorporation of new areas as human groups were enlarging their ranges of action. With this objective, updated archaeological data are presented in two different types of environments of the region: forests and highlands. These environments were marginal sectors that were not utilized as frequently or intensely as the valleys and where the archaeological record would be expected to preserve the actions associated with exploration contexts. The preliminary nature of data precludes defining exploratory contexts, but it is distinct in orienting its search in time and space.& COPY; 2023 Elsevier Masson SAS. All rights reserved
Diverse values of nature for sustainability
No full textTwenty-five years since foundational publications on valuing ecosystem services for human well-being(1,2), addressing the global biodiversity crisis(3) still implies confronting barriers to incorporating nature's diverse values into decision-making. These barriers include powerful interests supported by current norms and legal rules such as property rights, which determine whose values and which values of nature are acted on. A better understanding of how and why nature is (under)valued is more urgent than ever(4). Notwithstanding agreements to incorporate nature's values into actions, including the Kunming-Montreal Global Biodiversity Framework (GBF)(5) and the UN Sustainable Development Goals(6), predominant environmental and development policies still prioritize a subset of values, particularly those linked to markets, and ignore other ways people relate to and benefit from nature(7). Arguably, a 'values crisis' underpins the intertwined crises of biodiversity loss and climate change(8), pandemic emergence(9) and socio-environmental injustices(10). On the basis of more than 50,000 scientific publications, policy documents and Indigenous and local knowledge sources, the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) assessed knowledge on nature's diverse values and valuation methods to gain insights into their role in policymaking and fuller integration into decisions(7,11). Applying this evidence, combinations of values-centred approaches are proposed to improve valuation and address barriers to uptake, ultimately leveraging transformative changes towards more just (that is, fair treatment of people and nature, including inter- and intragenerational equity) and sustainable futures